Recuperator



C. E. LEHR RECUPERATOR Oct. `12, 1937.

5 Sheets-Sheet l Filed Feb. 6, 1937 gnuenfoz L() fr C. E. LEHR RECUPERATOR oct. 12, 1937,

3 Sheets-Sheet 2 Filed Feb. 6, 1937 f /H /N Ilnllll'lll IIIIIII.

[IIJ 'Ill' Patented Oct. 12, 1937 RECUPERATOR Pennsylvania Application February 6, 1937, Serial VNo.`124,422

8 Claims This invention relates to improvements in recuperator structures for pre-heating air or gas In recuperators of this type, considerable dif` culty has heretofore been experienced, due to the method of mounting the tubes in the terminal walls. The tubes were mounted rigidly in the wall blocks, no provision being made for eX- pansion and contraction of the tubes or of the wall. As a result, a great deal ofY breakage of the tubes took place, causing increased expense in operation as well as delays and inconvenience.

It is an object of this invention to provide a. recuperator having walls so constructed as to permit the tubes to be firmly and securely mounted therein, and at the same time to allow the tubes to expand and contract as necessitated without damage to the tubes.

It is a further object to provide means for sealing the openings in said terminal walls to prevent .leakage of gases.

The novel features of my invention will be more fully understood from the following description and claims taken with the drawings, in which Fig. 1 is a verticalV section of a three pass recuperator of the vertical type with my improved wall structure incorporated therein;

Fig. 2 is an enlarged end View of a portion of the terminal wall, with a part of the metal wall plate brokeny away;

Fig. 3 is a section along the line 3-3 of Fig'. 2; Fig. 4 is a. section along the line i--lI ofFig. 3, and

Fig. 5 is a section along the line 5-5 of Fig. 3.

Referring now to the drawings, Fig. 1 shows the furnace stack Ill with the recuperator structure II integral therewith. The recuperator has walls l2 and roof i3 which form the recuperator chamber I4. Walls I5 and horizontal wall I6 r divide the chamber It into compartments I1, I8 and I9. Communicating with chambers I8 and E9 through pipes 2li and 2I is fan 22 driven by motor 23. Air or gas to be preheated is admitted to the recuperator through duct 24 and is conveyed to the furnace through conduit 25. Waste gases from the furnace are conveyed to the recuperator through conduit 2S.

Terminal walls I5 are constructed of bricks or blocks 3U, the details of whose shape will be hereinafter described. Mounted in walls I5 are a.

plurality of Vrefractory tubes 3 I In the structure shown in Fig. 1, these tubes 3| are divided into three groups 32; 33 and 34 to form a three pass recupera-tor. Tubes 3l are provided with refractory cores 35 mounted withintubes 3l and spaced therefrom by pins 35. Metallic bolts or rods 31 pass through cores 35 and are held in place by ufshaped yokes or plates 38 and nuts 39; Walls I5 are covered yby heat-resisting metal plates 40 having openings therein for tubes 3l. Cupped metallic washers 4I have annular flanges 62 adapted to t into the ends of tubes 3I and beveledilanges'adapted to t tightly against metal vwall plates 4B. Washers 4I are held in tightY engagement with plates 40 by yokes 38.

Tubes 2l` are surrounded at their ends by packing or sealing material d.

Blocks are generally Y-shaped in cross-section. They are provided in their external faces with recesses 45 adapted to receive and retain sealing material 44. The top surfaces of the blocks are provided with ,bearing surfaces or shoulders 46, positioned almost intermediate the front and back faces of the block. The under surfaces of the blocks are'also provided with Yrecesses 45 for the receptionr of sealing material. The cut out portions 5D, 5I and 52 of blocks 3B are so proportioned that when in position they provide an opening of slightly larger diameter than that of tubes 3 I. This provides a clearance above thetubes SI, as clearly shown in Figs. 3, 4 and 5.Y The shoulders or bearing surfaces 45 support the bottom of the tubes and hold them out of' contact with the surface of blocks 3Q, except thatfportion of the blocks forming shoulders 46. This'provides aY clearance for the bottom half of the tubes 3l, also as shown in Figs. 3, 4 and 5. As a result, the tubes are free to expand and contract with practically no danger of breaking on account of rigid installation.

Blocks 3B may be of rebrick or similar inexpensive material, because, due to my improved construction, it is not necessary that the recuperator tubes and the terminal walls be made of materials having the same coefficient of eX- pansion. y

In cases where extremely high temperatures are developed in the waste gases, it may be desirable to build the terminal walls of a more highly refractory material in the location where the temperatures are highest. Thus, in Fig. 1, I have shown that portion of the terminal walls which contains group 34 of tubes 3l as built of the same refractory materials as the tubes. Iv employ in this portion of the terminal walls my improved shape of block 30, but the metal wall plates fw and cupped washers 4| may be dispensed with.

In operation, the hot waste gases from the furnace are conveyed to the recuperator through conduit 26 and pass upwardly, circulating about and heating tubes 3| and passing oif through stack I0. The air or gas to be heated enters through duct 24. It is drawn by fan 22 through groups 32 and 33 of tubes 3l, and compartments l1 and I8, and is blown through group 34 of tubes 3| and compartment I9, and to the furnace through conduit 25.

In actual operation, my improved form of construction has effected a considerable reduction in tube and wall breakage, with resultant economies in operation. Expensive delays for repair or replacement of cracked tubes and wall blocks are substantially eliminated, and waste of heat through leakage is greatly reduced.

While I have described my invention in considerable detail, I do not wish to be limited to such details, as numerous variations of my invention might be constructed without departing from the scope thereof.

Having thus described my invention, What I Claim and desire to secure by Letters Patent is: i

l. In a recuperator structure a tube terminal Wall having a tube passing therethrough, said wall providing a sealing recess around the extremity of the tube, and a bearing in offset relation to said recess for supporting the tube directly on the Wall and a clearance above the tube, whereby the portion of the tube above the bearing is unconiined with respect to the wall structure.

2. In a recuperator structure a tube terminal wall having a tube passing therethrough, said wall providing a sealing recess around the eX- tremity of the tube, a bearing in oiset relation to said recess for supporting the tube directly on the wall, a bottom clearance recess in offset relation to said bearing, and a top clearance recess above the bearing, whereby the portion of the tube above the bearing is unconned with respect to the wall structure.

3. In a recuperator structure a tube terminal wall having a tube passing therethrough, said wall being provided with a sealing recess around the extremity of the tube, a bearing in offset relation to said sealing recess for supporting the tube,

a clearance recess at the bottom of the tube in offset relation to said bearing, and a clearance recess above the tube in offset relation to said sealing recess.

4. In a recuperator structure a tube terminal wall having a tube passing therethrough, said Wall being provided with a sealing recess around the extremity of the tube, a bearing in offset relation to said sealing recess for supporting the tube, a clearance recess below the tube extending from said bearing to the inside face of the wall, and a clearance recess above the tube extending from said sealing recess to the inside face of the wall.

5. In a recuperator structure a tube terminal wall having a tube passing therethrough, said wall being provided with a sealing recess around the extremity of the tube, a bearing in offset relation to said sealing recess for supporting the tube, a clearance recess below the tube extending from Said bearing to the inside face of the wall, a clearance recess above the tube extending from said sealing recess to the inside face of the wall and sealing compound in said sealing recess only, whereby that portion of the tube inside of said bearing and said seal is unconned with respect to the wall structure.

6. In a recuperator structure, refractory tube terminal walls, tubes passing through said walls, means for sealing the tubes in the walls, heatresisting plates covering the outside faces of the walls, cupped Washers engaging said plates and openings defined by flanges engaging the ends of said tubes, yokes engaging said Washers, and bolts extending through the tubes and the yokes adapted to draw said washers against said plates, whereby to reduce leakage through said walls.

'7. In a recuperator structure, refractory block terminal walls, refractory tubes passing through said walls, means for sealing the ends of the tubes in the walls for a distance less than the thickness of the walls, means for sealing the joints between said blocks, heat-resisting plates covering the outside faces of the walls, cupped Washers engaging said plates and having central openings defined by the tubes, flanges adapted for entering the ends of yokes engaging said washers, cores positioned in the tubes, bolts extending through the cores and the yokes adapted to draw said washers against said plates, said tubes being normally of less length than the distance between the inside faces of the cupped Washers, whereby to allow free expansion of the tubes when heated and to reduce leakage through the joints in the walls.

8. In a recuperator structure, a tube terminal wall consisting of refractory blocks having complementary recesses arranged to form staggered openings for the reception of the ends of the tubes, said openings being formed so as to provide shallow tapered recesses around the ends of the tubes for the reception of packing, narrow Vbearing portions for the bottoms of the tubes intermediate said recesses and the inside face of the wall, and clearances above the tubes extending from said recesses to the inside face of the wall. i i i CHARLES E. LEHR. 

